Velocity apo monochromatic plane wave front inopararira nenzira yainojaira inonzi phase velocity ye wave. Sipidhi inofamba simba rechiedza inonzi ray velocity. Mafambiro anoita chiedza sekucherechedzwa neziso remunhu ndiyo nzira inofamba chiedza.

Kune isiri-magnetic single crystal, danho rekumhanya kwe planar light wave rinoenderana negwara rekufamba kwemagetsi. D uye magnetic field intensity H, nepo simba rekuparadzira gwara rechiedza wave riri perpendicular to H uye kusimba kwemunda wemagetsi E. Dielectric constant yeanisotropic optical media ndeyechipiri-order tensor.D uye E kazhinji hadzina kufambirana, saka kutungamira kwechikamu chevelocity v uye linear velocity v_r kazhinji hadziwirirani. Iyo yaisanganisira Angle α pakati pavo inonzi discrete angle, inova basa rekutungamira kwechikamu chevelocity (kana ray velocity) uye nzira ye D (kana E) (sezvinoratidzwa mumufananidzo uri pasi apa). The phase velocity uye linear velocity kazhinji haina kuenzana, uye hukama huripo pakati pavov=v_rcosα.

Reshiyo yekukurumidza kunofamba chiedza muvacuum (c) kusvika padanho rayo velocity v mune yakapihwa gwara mune anisotropic optical medium inodaidzwa kuti refractive index yenzira iyoyo. Saizvozvowo, chiyero chec kune kumhanya kwemwaranzi mune imwe nzira n_r=c/v_r inonzi refractive index yemwaranzi munzira iyoyo.

WISOPTIC wave-plates